Oxidative attack of proteins may produce cleavage of the peptide chain, among other effects. The carboxyl end of such cleavage should contain low molecular weight non-amino acids as a signature of such cleavage. It is hoped to demonstrate this signature in cleaved proteins. HPLC and gas chromatograph/mass spectrometric analyses of low molecular weight volatile acids have been developed and attempts to demonstrate the presence of the acids in oxidized protein have been begun.